This invention relates to an air conditioner for a vehicle, and in particular, to an air conditioner of this type which serves high cooling capacity of an evaporator with a lower fuel consumption even, for example, on an idle running of an engine.
As well known in the art, an air conditioner for a vehicle generally comprises refrigerating cycle including at least a compressor, a condenser, an expansion valve, and an evaporator. The compressor compresses gasified refrigerant into compressed refrigerant. The condenser condenses the compressed refrigerant into liquid refrigerant. The liquid refrigerant is then supplied to the expansion valve. The expansion valve expands the liquid refrigerant into sprayed refrigerant. The sprayed refrigerant is evaporated in the evaporator. In some cases, the refrigerating cycle also includes a receiver and an undercooling heat exchanger. Such an air conditioner is disclosed in a Japanese Unexamined Utility Model Prepublication No. Jikkai-hei 2-56711. The air conditioner comprises the heat exchanger between the receiver and the evaporator in the refrigerating cycle. The heat exchanger is disposed at the front end of a car body so as to improve the cooling capacity of the evaporator by increasing a degree of undercooling of the liquid refrigerant, utilizing ventilation through a damper or blast from an electric fan.
In the conventional air conditioner, the degree of undercooling is relatively low when the undercooling is carried out, on the idle running of the engine or on a traffic jam, by using the blast from the electric fan. More specifically, the electric fan is supplied with the hot air affected by heat irradiation from an engine so that the cooling capacity of the evaporator is less improved. In addition, it is necessary to increase engine speed for properly operating the electric fan.